1971931931 has 2 divisors, whose sum is σ = 1971931932. Its totient is φ = 1971931930.

The previous prime is 1971931903. The next prime is 1971931961. The reversal of 1971931931 is 1391391791.

It is a weak prime.

It is an emirp because it is prime and its reverse (1391391791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1971931931 - 2¹⁰ = 1971930907 is a prime.

It is a super-2 number, since 2×1971931931² = 7777031080994777522, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1971931901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 985965965 + 985965966.

It is an arithmetic number, because the mean of its divisors is an integer number (985965966).

Almost surely, 2^1971931931 is an apocalyptic number.

1971931931 is a deficient number, since it is larger than the sum of its proper divisors (1).

1971931931 is an equidigital number, since it uses as much as digits as its factorization.

1971931931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 45927, while the sum is 44.

The square root of 1971931931 is about 44406.4401973407. The cubic root of 1971931931 is about 1253.9993358835. Note that the first 3 decimals are identical.

The spelling of 1971931931 in words is "one billion, nine hundred seventy-one million, nine hundred thirty-one thousand, nine hundred thirty-one".